1. Field of the Invention
This invention relates to a knocking control device, and, more particularly, to a knocking control device for a watercraft engine.
2. Description of the Related Art
A knocking control device for an automobile engine is described in JP-A-2001-082242. This knocking control device is equipped with a control function to determine whether the fuel has a high octane number or a low octane number from a signal of a knock sensor. This is done even though the engine, which is specified for high octane number gasoline, is supplied with regular gasoline. The device is also provided with a knocking learning control routine under which an ignition timing map for the high octane number and another ignition timing map for the low octane number are complementarily mixed at a certain rate with each other to determine ignition timing. A coefficient of the rate for the complemental mixing is called a knocking learning value.